85 Io

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85 Io
Discovered byC. H. F. Peters
Discovery dateSeptember 19, 1865
A899 LA; A899 UA
Main belt
Orbital characteristics
Epoch March 6, 2006 (JD 2453800.5)
Aphelion473.341 Gm (3.164 AU)
Perihelion320.334 Gm (2.141 AU)
396.837 Gm (2.652 AU)
1578.081 d (4.32 a)
18.12 km/s
Physical characteristics
Dimensions180×160×160 km[1][4]
Mass~3.4×1018 (estimate)
Mean density
~1.4 g/cm³ (estimate)[5]
~0.028 m/s² (estimate)
~0.07 km/s (estimate)
0.2864 d (6.875 h) [2]
Albedo0.067 [3]
Temperature~172 K
max: 272K (-2° C)
Spectral type
C-type asteroid

85 Io is a big, dark Main belt asteroid of the C spectral class. It is probably a primitive body made of carbonates. Like 70 Panopaea it orbits within the Eunomia asteroid family but it is not related to the shattered parent body.

Io is a retrograde rotator, with its pole pointing towards one of ecliptic coordinates (β, λ) = (-45°, 105°) or (-15°, 295°) with a 10° uncertainty[1]. This gives an axial tilt of about 125° or 115°, respectively. Its shape is quite spherical.

It was found by C. H. F. Peters on September 19, 1865 and named after Io, a lover of Zeus in Greek mythology.

A diameter of 178 kilometres was measured from an occultation of a star on December 10, 1995 [4].

Io is also the name of the volcanic moon of Jupiter. With a two-digit number and a two-letter name, 85 Io has the shortest designation of all minor planets.

Other websites[change | change source]

References[change | change source]

  1. PDS lightcurve data
  2. A. Erikson Photometric observations and modelling of the asteroid 85 Io in conjunction with data from an occultation event during the 1995-96 apparition, Planetary and Space Science, Vol. 47, p. 327 (1999).
  3. G. A. Krasinsky et al. Hidden Mass in the Asteroid Belt, Icarus, Vol. 158, p. 98 (2002).